Certain types of absorbent articles such as sanitary napkins and incontinence protectors for lightly incontinent female users are intended to be worn in close contact against the body of the user. Such an absorbent article is thereby usually applied inside the panties of the user and is kept in contact against the body by the pressure from the panties during use.
It is important that the surface of an absorbent article which is intended to be facing the body of the user is soft and comfortable and does not cause irritation. Furthermore, the surface of the article should have the ability to receive the body fluid which is emitted to the article, and rapidly let the liquid pass into the article and be absorbed by it. If the liquid is not admitted into the article sufficiently quickly, the risk is obvious that the liquid instead will flow onto the surface of the article and cause leakage. Furthermore, the surface of the article will become wet and sticky, something which is perceived as extremely unpleasant by a majority of users. A wet surface may further cause the user inconvenience in the form of skin irritation.
In order to avoid wet surfaces on absorbent articles, these are generally provided with a liquid-pervious surface layer of a comparatively hydrophobic material. Examples of such hydrophobic materials are perforated plastic films, plastic scrims and nonwoven materials of hydrophobic fibres. The term nonwoven material refers to different types of non-woven, bonded fibre layers. Such hydrophobic layers have a very low wettability and are therefore usually treated, for example, with surfactants in order to increase the wettability and the ability to admit liquid through. In spite of this, the acquisition rate of hydrophobic surface materials is often too low.
The hydrophobic surface layers exhibit a very dry surface, even after wetting. However, small liquid quantities may remain in or on the surface layer after wetting, since the liquid transportation ability in a hydrophobic surface layer is low. It is true, for instance, that a perforated plastic layer has good liquid transportation ability through the perforations, but liquid which has ended up between the perforations tends to remain on the surface.
Remaining liquid in or on the liquid-pervious surface layer constitutes a problem, in particular when the absorbent article is a sanitary napkin, since menstrual fluid has a relatively high viscosity and thereby has a larger inclination to leave residues on the liquid-pervious cover layer. Such remaining liquid results in the surface of the sanitary napkin becoming wet and sticky, which is a disadvantage both during use and when the sanitary napkin shall be replaced.
Since an absorbent article, such as a sanitary napkin or an incontinence protector, usually is attached inside the panties of the user by adhesive surfaces arranged on the article, the article follows the movements of the panties during use. This implies that the position of the article is changed somewhat in relation to the body of the user when the user moves about. In this way, liquid which has remained on the surface of the article will be smeared out across the surface. The soiled surface bears on the body of the user, something which of course is perceived as unpleasant and insanitary.
Absorbent articles for female users are sometimes provided with a hump, intended to be arranged in the genital region of the user during use, in order to catch body fluid as soon as it leaves the body of the user. Such a hump may thereby completely, or partially, be placed between the labia pudendi of the user, and will thereby come into contact with the mucous membranes inside the labia pudendi. Thereby, it has been found that the, proportionately, very dry surface on a conventional hydrophobic surface layer can cause discomfort in the form of chafing and irritation of the mucous membranes.
By means of the present invention, however, an absorbent article has been achieved with which the problems associated with previously known such articles essentially have been eliminated. Accordingly, by means of an article according to the invention it is possible to offer both a dry surface against the skin of the user, rapid liquid acquisition and minimal irritation of the mucous membranes of the user.
An article designed in accordance with the invention is primarily characterized in that the wetting region of the user-facing side of the article is constituted of a hydrophilic absorbent material, at least at a surface of the article which is intended to be facing the user during use, and in that the remaining parts of the user-facing side of the article are constituted of a hydrophobic material.
The hydrophilic portion of the user-facing side may come into contact with the mucous membranes of the user in the genital region during use. Since the hydrophilic material is able to retain moisture, desiccation of the mucus membranes is counteracted.
Advantageously, the hydrophilic material has a certain absorbency of its own, so that liquid is not only absorbed into the voids of the material, but also into the material itself. For instance, it is suitable to use a fibre material in which at least some of the integral fibres have the ability to absorb liquid into the fibres. Thereby, the risk that the hydrophilic material is entirely drained of liquid by underlying absorption material is non-existent. Accordingly, such an absorbent material will maintain a wet surface bearing on the mucous membranes of the user during use.
The article, according to the invention, may advantageously be provided with a hump, projecting from the user-facing side, wherein the location of the hump on the article at least partially coincides with the wetting region. By means of arranging a hump at the wetting region, it is ensured that the hydrophilic region of the article is in contact against the mucous membranes of the user during use and prevents desiccation of these. Preferably, the hump is shaped in such a way that it conforms to the body shape of the user in the region in question, whereby the risk of placing the article in the wrong position is minimal. An anatomically correct design of a hump on the article contributes moreover to the article being directed into and being kept in the correction position in relation to the genitals of the user.
A hump of the herein intended type may, for example, be achieved by means of the absorbent article comprising shaping members which, through the action of the forces which the article is subjected to during use, have the ability to bring the wetting region of the article into contact with the mucous membranes of the user. Such shaping members may, for example, be constituted of compressions, folding notches or the like, or of a deformable insert.
The hydrophilic material in the liquid-pervious surface layer may, for example, primarily consist of hydrophilic, absorbent fibres such as cellulose fibres, cotton, rayon, jute, peat moss, or the like. Alternatively, the hydrophilic material in the liquid-pervious surface layer may primarily consist of hydrophilic absorbent foam material, such as polyurethane foam, cellulose foam, or the like.
The hydrophobic material in the liquid-pervious surface layer may, for example, primarily consist of hydrophobic fibres such as polypropylene fibres, polyethylene fibres, polyester fibres, or hydrophobic bi-component fibres, or of a hydrophobic foam material, such as polyethylene foam.
Although it is preferred, the liquid-pervious surface layer does not have to be composed of different components, but may consist of one and the same material layer, which has been treated so that it has different properties within different regions of its surface. Accordingly, the hydrophilic material in the liquid-pervious surface layer may be constituted of a hydrophobic material which has been rendered hydrophilic. In a corresponding way, the hydrophobic material in the liquid-pervious surface layer may of course be constituted of a hydrophilic material which has been rendered hydrophobic.
A number of different types of treatment for modifying the surface and changing the surface properties of materials for absorption purposes are well-known to the person skilled in the art. The most common way to achieve hydrophilicity for an initially hydrophobic material, is to treat the material with a wetting agent. The largest disadvantage of treatment with a wetting agent, however, is that the wetting agent gradually is flushed out of the material, whereafter this returns to its initial hydrophobic state. Also other methods for rendering a hydrophobic material hydrophilic are previously known, such as flame treatment, corona or plasma.
According to one embodiment of the invention, the liquid-pervious user-facing side comprises a laminate of a first liquid-pervious, hydrophobic material layer, arranged closest to the absorbent body, and a second liquid-pervious, hydrophilic material layer of substantially the same extension as the wetting region of the article, and intended to bear on the body of the user in the wetting region during use.
According to another embodiment of the invention, the liquid-pervious user-facing side comprises a laminate of a first liquid-pervious, hydrophobic material layer, and a second liquid-pervious, hydrophilic material layer arranged closest to the absorbent body, inside the first material layer, wherein the hydrophobic material layer exhibits an opening of substantially the same extension as the wetting region of the article through which the hydrophilic layer is exposed.
It is an advantage if the absorbent article is kept in position against the body of the user without being attached to the underwear of the user. The article may thereby, for instance, have such a shape and stiffness that it remains in position against the body of the user without the need for a special attachment member. Suitably designed articles are described in, for example, SE 9604224-7, SE 9604222-1 and SE 9604223-9. Alternatively, the article may be kept in position against the body of the user by means of a girdle, or the like, which is detached from the panties.
Particularly when such articles which initially are essentially planar are concerned, it may be suitable to provide the article with some kind of shaping member which, preferably by means of influence of the forces which the article is subjected to during use, has the ability to bring the wetting region into contact with the mucous membranes of the user. Examples of such shaping members are folding notches, such as compressions or slits, and stiffening inserts, with or without hinge-like portions. Furthermore, it is possible to use different types of elastic means or elements which the user herself bends or forms in another way before use.